Custom frame and seat tube angle

Greetings Lee. I am in the process of having a custom hardtail frame built, I have some questions about fit, seat tube angle, pedaling efficiency & comfort. Seems like a lot of makers are going with shorter stays and steeper 74* seat tube angles to keep the rider weight centered. My Builder thinks that a true 73* seat tube angle will work fine with short stays. Of course I want to be sure about the geometry.

Wondering what your take is on the steeper seat angles paired with shorter stays – certainly for short rides they can keep the rider in a good spot, but does that come at price – less engagement of the glutes & lower back, and thus less ideal for longer days in the saddle, for example?

Thanks for any input.
Josh

Josh,

Thoughts:

When you look at variations in seatpost setback and the fore-aft adjustment via saddle rails, a degree of seat tube angle isn’t a big deal. You can probably position your saddle with either angle.

I think some of the enduro bikes are going steeper to make more room for the rear wheel and big travel. Human bodies have not changed.

Enduro bikes have rear sag, while hardtails don’t. On a bike with more rear sag than front sag, the seat tube angle will get slacker when you’re on the bike. So that 74 might become a 73, especially while you’re seated on a steep hill.

If you’re getting a custom frame built, figure out exactly where your saddle needs to be in relation to your bottom bracket, then design from there. Every bike I ride sitting down has the same saddle (Specialized Henge Expert 143mm) with almost identical seat-to-feet relationship. IMPORTANT: My ideal setup isn’t what “fitters” suggest, and it’s probably not yours. Our bodies are different. If you don’t know what you need, and your current bike feels OK, match your current bike.

I strongly suggest you look at the bike setup material at the Lee Likes Bikes MTB School. I have a full system to position your handlebars for optimal power and control. It also has a calculator to help you determine your frame’s ideal reach and stack. This is cheap insurance when you’re buying an expensive bike!

Learn more at www.llbmtb.com >>>

I hope that helps,

Lee

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